Apparatus for processing oilseed and grain mash products

Abstract

An extruder for oilseed products, grain mash, and other materials includes an elongated screw rotatably disposed in a bore formed in a tubular housing. The screw is characterized by a plurality of separate threads of progressively decreasing pitch toward a discharge end of the screw. The separate threads are spaced apart and thread portions of constant pitch include gaps to provide clearance for radially inwardly projecting pins disposed in the housing and projecting into the material flow path for mixing the material to prevent solidification thereof and clogging of the extruder. The screw shaft includes spaced apart annular collars which comprise backflow dams for the material being conveyed through the extruder. The tubular extruder housing is of modular construction and is adapted to be used with various combinations of tubular inserts and a plurality of stacked annular rings forming the extruder bore. The rings are provided with radially extending channels for draining liquid being extruded from the material out of the bore. The extruder is provided with spaced apart electrical resistence heating elements disposed on the housing for heating the material being extruded. Temperature sensors disposed in the mixing pins sense the temperature of the material in the extruder flow path.

What I claim is: 
     
       1. An extruder for processing material such as oilseed products, grain mash and the like and comprising: an elongated housing including means defining a substantially continuous cylindrical bore;   inlet conduit means in communication with said bore;   means forming a discharge opening at one end of said bore;   an elongated rotatable screw conveyor disposed in said bore and including screw thread means disposed on a cylindrical shaft and forming a substantially spiral flow path for said material; and   a plurality of spaced annular surfaces formed on said shaft at axially spaced gaps in said thread means and facing said one end of said bore to provide resistance to flow of material toward said inlet conduit from said one end of said bore.   
     
     
       2. An extruder for processing material such as oilseed products, grain mash and the like and comprising: an elongated housing including means defining a cylindrical bore;   inlet conduit means in communication with said bore;   means forming a discharge opening at one end of said bore opposite said inlet conduit means; and   an elongated rotatable screw conveyor disposed in said bore and including screw thread means forming a substantially spiral flow path for said material, said screw thread means including a plurality of separate thread portions of a different pitch disposed around respective cylindrical shaft portions of said conveyor, the diameters of said respective shaft portions being different for said thread portions of different pitch, the pitch of said thread portions decreasing progressively toward said one end of said bore, and the diameter of said respective shaft portions increasing with decreasing pitch of said thread portions.   
     
     
       3. An extruder for processing material such as oilseed products, grain mash and the like and comprising: an elongated housing including means defining a cylindrical bore;   inlet conduit means in communication with said bore;   means forming a discharge opening at one end of said bore opposite said inlet conduit means; and   an elongated rotatable screw conveyor disposed in said bore and including screw thread means forming a substantially spiral flow path for said material, said screw thread means including a plurality of separate thread portions of a different pitch disposed around respective cylindrical shaft portions of said conveyor, the diameter of said respective shaft portions being different for said thread portions of different pitch, said respective shaft portions of different diameter being interconnected by shaft portions forming frustoconical surfaces.   
     
     
       4. The invention set forth in clalim 3 wherein: at least some of said shaft portions forming said frustoconical surfaces include a transverse annular surface delimiting the base of said shaft portions and facing toward said one end of said bore.   
     
     
       5. An extruder for processing material such as oilseed products, grain mash and the like and comprising: an elongated housing including means defining a cylindrical bore;   inlet conduit means in communication with said bore;   means forming a discharge opening at one end of said bore opposite said inlet conduit means; and   an elongated rotatable screw conveyor disposed in said bore and including screw thread means forming a substantially sprial flow path for said material, said screw thread means including a plurality of separate thread portions of a different pitch disposed around respective cylindrical shaft portions of said screw conveyor, the diameter of said shaft portions being different for said thread portions of different pitch; and   means on said shaft portions forming a plurality of spaced apart annular surfaces facing said one end of said bore.   
     
     
       6. The invention set forth in claim 5 wherein: said annular surfaces are formed at said gaps between said separate thread portions.   
     
     
       7. An extruder for processing materials such as oilseed products, grain mash, and the like and comprising: an elongated housing including means forming a cylindrical bore therein;   inlet conduit means in communication with said bore;   means forming a discharge opening at one end of said bore opposite said inlet conduit means;   an elongated rotatable screw conveyor disposed in said bore and forming a substantially spiral flow path for material through said bore, said conveyor comprising a plurality of separate thread portions of different pitch formed on respective axially spaced portions of a conveyor shaft, the pitch of the threads of said thread portions decreasing progressively toward said one end of said bore, and the diameter of said respective shaft portions increasing progressively toward said one end of said bore, and means comprising a plurality of spaced apart radially inwardly extending projections supported on said housing and extending into said bore and said flow path for causing material to mix as it passes along said flow path and to prevent clogging of said flow path by said material.   
     
     
       8. The invention set forth in claim 7 wherein: at least some of said projections are disposed betweeen said thread portions of different pitch.   
     
     
       9. The invention set forth in claim 7 wherein: said thread portions of different pitch include an interruption in said thread forming an axially extending gap to provide clearance for respective ones of said projections.   
     
     
       10. The invention set forth in claim 7 together with: temperature sensing means disposed in at least one of said projections for sensing the temperature of material flowing past said one projection in said flow path.   
     
     
       11. The invention set forth in claim 10 together with: heating element means associated with said housing for heating said material in said bore.   
     
     
       12. An extruder for processing material such as oilseed products, comprising: an elongated housing including means forming a cylindrical bore;   inlet conduit means in communication with said bore;   a discharge opening in said bore at one end of said bore opposite said inlet conduit means;   an elongated screw conveyor rotatably disposed in said bore, said conveyor comprising a plurality of thread portions of different pitch, the pitch of respective ones of said thread portions decreasing progressively toward said one end of said bore to provide progressively greater compaction of material being conveyed toward said discharge opening;   heating element means disposed on said housing for heating material as it is being conveyed through said bore by said conveyor; and   passage means in said housing opening into said bore at a point on said housing between said heating element means and said one end of said bore for draining liquid extracted from said material after preheating of said material by said heating element means.